Professor, Institute for Materials Research, Tohoku University, Japan.

Speech Title: Bias-current Modulation Method for Improving the Analytical Performance in Radio-frequency Glow Discharge Plasma Optical Emission Spectrometry
Abstract: A modulation detection technique using a fast Fourier transform (FFT) analyzer is described to estimate the emission intensity from a radio-frequency (RF)-powered glow discharge plasma with better precision, and eventually to obtain more precise analytical results for the atomic emission analysis. In an RF glow discharge plasma, a dc bias current can be introduced by connecting an external electric circuit with the discharge lamp, which predominantly enhances the emission intensities. Further, the bias current can be pulsated with a switching device to modulate the emission intensities, and then the modulated component was selectively detected with an FFT analyzer, which has an ability to disperse the components by frequency from an overall signal. This method could be applied to determination of impurity elements in metallic materials.
Keywords: metallurgical analysis; atomic emission spectrometry; glow discharge plasma; bias current modulation; fast Fourier transform analyzer